Diabetes Prevention Program (DPP)

The NIDDK-sponsored Diabetes Prevention Program (DPP) and ongoing DPP Outcomes Study (DPPOS) are major studies that changed the way people approach type 2 diabetes prevention worldwide. The DPP showed that people who are at high risk for type 2 diabetes can prevent or delay the disease by losing a modest amount of weight through lifestyle changes (dietary changes and increased physical activity). Taking metformin, a safe and effective generic medicine to treat diabetes, was also found to prevent the disease, though to a lesser degree.

The DPPOS has continued to follow most DPP participants since 2002. To date, the DPPOS has shown that participants who took part in the DPP Lifestyle Change Program or are taking metformin continue to prevent or delay type 2 diabetes for at least 15 years. The DPPOS has also shown that the DPP Lifestyle Change Program is cost effective (costs are justified by the benefits of diabetes prevention, improved health, and fewer health care costs) and metformin is cost-saving (leads to a small savings in health care costs) after 10-years. DPPOS researchers are also continuing to follow other health problems in participants such as cancer, cardiovascular diseases (heart and blood vessel disease), nerve damage, kidney disease, and eye disease. As participants age, researchers are following age-related health problems such as trouble with physical function and difficulties with thinking or memory.

The NIDDK built on the success of the DPP by funding additional research to make modified versions of the DPP Lifestyle Change Program that are more cost-effective and more easily available to the tens of millions of Americans at risk for type 2 diabetes. Several modified group versions of the DPP Lifestyle Change Program have shown great promise. One version tested in YMCAs is now widely available in the United States through a partnership with the CDC’s National Diabetes Prevention Program. Beginning in 2018, Medicare will cover participation in the CDC’s National Diabetes Prevention Program for those who are eligible.

Diabetes Prevention Program (DPP)

DPP Goal

The DPP looked at whether the DPP Lifestyle Change Program or taking metformin would delay or prevent type 2 diabetes.

DPP Results

After about 3 years, the DPP showed that participants in the DPP Lifestyle Change Program lowered their chances of developing type 2 diabetes by 58 percent compared with participants who took a placebo (a pill without medicine). The DPP Lifestyle Change Program was effective for all participating racial and ethnic groups and both men and women. The Program worked particularly well for participants ages 60 and older, lowering their chances of developing type 2 diabetes by 71 percent. About 5 percent of participants in the DPP Lifestyle Change Program developed diabetes each year during the study compared with 11 percent of participants who took a placebo.

Participants who took metformin lowered their chances of developing type 2 diabetes by 31 percent compared with participants who took a placebo. Metformin was effective for all participating racial and ethnic groups and both men and women. Metformin was most effective in women with a history of gestational diabetes, in people between the ages of 25 and 44, and in people with obesity who had a body mass index of 35 or higher.

DPP Study Design

The DPP was a randomized, controlled clinical trial conducted at 27 clinical centers around the United States from 1996 to 2001. The trial enrolled 3,234 participants; 55 percent were Caucasian, and 45 percent were from minority groups at high risk for the disease, including African American, Alaska Native, American Indian, Asian American, Hispanic/Latino, or Pacific Islander. The trial also recruited other groups at high risk for type 2 diabetes, including people ages 60 and older, women with a history of gestational diabetes, and people with a parent, brother, sister, or child who had type 2 diabetes.

DPP participants were randomly assigned to one of the following groups:

Lifestyle Change Group – Group participants joined a DPP Lifestyle Change Program that provided intensive training. Participants tried to lose 7 percent of their body weight and maintain that weight loss by eating less fat and fewer calories and exercising 150 minutes per week. Researchers met with participants individually at least 16 times in the first 24 weeks, and then every 2 months with at least 1 phone call between visits.

Metformin Group – Group participants took 850 mg of metformin twice a day and were provided standard advice about diet and physical activity.

Placebo Group – Group participants took a placebo twice a day instead of metformin and were provided standard advice about diet and physical activity.

DPP participants who developed diabetes remained in the study and received additional care from their own physicians if good blood glucose control could not be maintained.

After DPP ended all participants were provided a modified group version of the DPP’s Lifestyle Change program.

Diabetes Prevention Program Outcomes Study (DPPOS)

DPPOS Goal

The DPPOS is following DPP participants to see if participants who took part in the DPP Lifestyle Change Program or who are continuing to take metformin have a delay in the development of type 2 diabetes over time and if they experience fewer health problems such as cancer, cardiovascular diseases, nerve damage, kidney disease, eye disease, and age-related health problems such as trouble with physical function and difficulties with thinking or memory.

DPPOS Results

10-Year Findings

At the 10-year follow-up

participants who took part in the DPP Lifestyle Change Program continued to have a delay in the development of diabetes by 34 percent—and developed diabetes about 4 years later—compared with participants who took a placebo. Participants from the DPP Lifestyle Change Program ages 60 and older had a delay in the development of diabetes by 49 percent.

participants who continued to take metformin had a delay in the development of diabetes by 18 percent—and developed diabetes about 2 years later—compared with participants who took a placebo.

participants from the DPP Lifestyle Change Program and participants who continued to take metformin or took a placebo all improved their risk factors for cardiovascular diseases, such as high blood pressure and cholesterol. However, the participants from the DPP Lifestyle Change Program achieved these results with fewer blood pressure and cholesterol-lowering medications.

the DPP Lifestyle Change Program was shown to be cost-effective and metformin was shown to be cost-saving.

15-Year Findings

At the 15-year follow-up

participants from the DPP Lifestyle Change Program continued to have a delay in the development of diabetes by 27 percent compared with participants who took a placebo.

participants who continued to take metformin had a delay in the development of diabetes by 18 percent compared with participants who took a placebo.

about half (55 percent) of participants from the DPP Lifestyle Change Program and 56 percent of participants who continued to take metformin developed diabetes compared with 62 percent of participants who took a placebo.

there were no overall differences in small blood vessel problems such as those found in eyes, nerves, and kidneys between participants from the DPP Lifestyle Change Program and participants who continued to take metformin or took a placebo. However, women from the DPP Lifestyle Change Program developed fewer small blood vessel problems than participants who continued to take metformin or took a placebo. Participants who did not develop diabetes had a 28 percent lower rate of small blood vessel problems compared with participants who developed diabetes.

Current Focus

In early 2016 the NIDDK, in partnership with the National Heart Lung and Blood Institute (NHLBI) and National Cancer Institute (NCI), began funding a third phase of DPPOS—proposed to last 10 years—to find out if people who are at high risk for type 2 diabetes and take metformin have lower rates of cardiovascular diseases and cancer, as suggested by several earlier small-scale studies.

DPPOS Study Design

The DPPOS follow-up study started in 2002. All 3,149 surviving participants of DPP groups were eligible for the DPPOS, including those with and without diabetes. Of the 3,149 surviving participants, 2,776 (88 percent) joined the DPPOS. Similar proportions of each DPP group joined the DPPOS and remained in their original groups. There were some changes to the treatments each group received:

Lifestyle Change Group –Group participants received quarterly group lifestyle change classes throughout the study and two group classes yearly to reinforce self-management behaviors for weight loss.

Metformin Group – Group participants received quarterly group lifestyle change classes throughout the study. Participants continued to take metformin and were told that they were taking metformin.

Placebo Group – Group participants received quarterly group lifestyle change classes throughout the study. Participants did not take a placebo pill.

DPPOS participants who developed diabetes remained in the study and received additional care from their own physicians if good blood glucose control could not be maintained.

Related Health Information

CDC’s National Diabetes Prevention Program – The CDC’s National Diabetes Prevention Program uses key components of the DPP—lifestyle changes such as physical activity and weight loss—to prevent or delay the start of type 2 diabetes.

Related Studies

Scalable modified versions of the DPP Lifestyle Change Program– Researchers are making modified group versions of the DPP Lifestyle Change Program—such as the YMCA’s Diabetes Prevention Program—that are more cost-effective and more easily available to Americans at risk for type 2 diabetes.

Action for Health in Diabetes (Look AHEAD) Study – Look AHEAD used an intensive lifestyle change program modeled on the DPP Lifestyle Change Program to study how diet and physical activity affect heart attack, stroke, and cardiovascular disease-related death in people who already had type 2 diabetes.

Vitamin D and Type 2 Diabetes (D2d) – This ongoing study is examining whether vitamin D supplements can reduce or delay development of type 2 diabetes in people at high risk for the disease.

Studies on lifestyle change – Researchers are looking at cost-effective ways to teach people about lifestyle change and weight loss, such as in group settings and over the internet.

Ancillary studies of DPP and DPPOS data – Researchers continue to study DPP and DPPOS data. One study found that DPP participants carrying two copies of a gene mutation were at a higher risk of developing diabetes but benefited from lifestyle changes as much as, or more than, those without the gene mutation. Another study found that weight loss was the main way to predict whether a participant in the DPP Lifestyle Change Program would have a lower risk of developing diabetes. Researchers said that risk-reduction efforts should focus on weight loss, which is helped by increased physical activity.